Atmospheric closed hot water tank system with separate expansion control

ABSTRACT

This invention relates to dispensers which require a source of hot water and more particularly comprises a hot beverage dispenser having a new and improved hot water heating system. Most commercial hot water sources do not provide water at a high enough temperature so that it may be mixed with other ingredients in a food dispenser and be served directly without supplemental heating. Consequently some form of hot water heater is used in combination with a holding tank in most hot water systems. The systems take a number of different forms; for example, they may employ a closed or open tank, and those systems which use a closed tank may either be pressurized or unpressurized. All of the various sytems used heretofor have certain disadvantages which are described below.

United States Patent 1191 Gardner, Jr. et al.

[ 1 JuneS, 1973 [75] lnventors: John A. Gardner, Jr., Tewksbury; MerleS. Brown, Cohasset; William H. Jacobs, Brookline, all of Mass.

[73] Assignee: Jet Spray Cooler, Inc., Waltham,

Mass.

22 Filed: Sept. 13, 1971 21 Appl.No.: 180,031

3,586,214 6/1971 Diebel ..222/l29.4

Primary Examiner-Samuel F. Coleman Attorney-Wolf, Greenfield & Sacks I[57] ABSTRACT This invention relates to dispensers which require asource of hot water and more particularly comprises a hot beveragedispenser having a new and improved hot water heating system.

Most commercial hot water sources do not provide water at a high enoughtemperature so that it may be mixed with other ingredients in a fooddispenser and be served directly without supplemental heating.Consequently some form of hot water heater is used in combination with aholding tank in most hot water systems. The systems take a number ofdifferent forms; for example, they may employ a closed or open tank, andthose systems which use a closed tank may either be pressurized orunpressurized. All of the various sytems used heretofor have certaindisadvantages which are described below.

10 Claims, 2 Drawing Figures PATENTEDJUH 5197s FIG.|

FIG. 2

ATMOSPHERIC CLOSED HOT WATER TANK SYSTEM WITH SEPARATE EXPANSION CONTROLBACKGROUND PRIOR ART Most hot water storage tanks used in hot beveragedispensers deliver water on demand at l75l 85F. Resistance water heatersare either directly immersed in the water or are placed in heat exchangerelationship with the tank walls to elevate the water temperature.Normally an adjustable thermostat is used to preset and control thewater temperature automatically at a desired temperature level. The hotwater systems also include a solenoid valve to control the discharge ofwater from the tank, and a flow regulating valve is used to maintain afixed flow rate during a preset drink dispensing cycle.

One system commonly used employs a closed, pressurized tank. Because thetank is pressurized, substantial cost is involved in tank constructionto accommodate the tank pressures, and provisions must be made forrelieving excessive pressures. Difficulties with this system areencountered typically upon thermostat failure. When failure occurs inthe operating condition during a period when the dispenser is not beingused, (typically overnight), the water temperature and resultantpressure rises until some form of safety device provided in the tankrelieves the pressure. Since the tanks in such systems are directlyconnected to the incoming water line, the pressure build up associatedwith such thermostat failure has a tendency to back up in the system.Consequently, when a drink is drawn under such conditions the water willjet violently from the outlet and may result in injury to the operator.

Pressurized systems generally are less complex than systems whichoperate at atmospheric pressure. For example, ordinarily no externalarrangement is required to compensate for expansion of incoming coldwater. Compensation is rather achieved through the compression of theair in the head space in the tank above the tank water outlet. Aconcomitant disadvantage of this feature, however, is that the airchamber collects gases which evolve from water during heating, such aschlorine, sulfur dioxide, etc., and the concentration of such gases inthe tank imparts an off-taste to the water which is subsequentlydispensed, and the hot drink of course is adversely effected.

Another commonly used system employs an open tank operating atatmospheric pressures. This type of system requires the use of somefloat or other signalling device in combination with a solenoid valve tomaintain the water level and compensate for water expansion. A secondsolenoid is required in such systems to control water discharge duringthe drink dispense cycle.

Open atmospheric tanks require that the tank be elevated with respect tothe location of the mixing chamber in the dispenser where water and theflavor concentrate are combined, to achieve maximum hydrostatic head tospeed the discharge flow rates from the tank. This necessarily limitsthe design of the dispenser. And in such systems relatively large ductsof minimum length and free of bends and restrictions are used tomaximize flow rates. Further, the discharge line must leave the tank atthe bottom and be free of dips and rises that form traps in the linewhere the water may cool.

Yet a third commonly used system includes a closed tank operated atatmospheric pressure. This system requires automatic compensation forwater expansion upon heating. The solenoid and flow regulators arelocated in the inlet line to the tank and isolate the line pressure fromthe tank. Such a system may be classified as a displacement fill systembecause water discharges from the top of the tank upon the introductionof water into the tank at the bottom.

While closed atmospheric pressure tanks are widely used, they have manydisadvantages. Without provision of some form of expansion control,expansion water continually drips from the tank as cold water expandsupon heating. The expansion control ordinarily provided includes anaspirator in the form of a jet pump and an expansion reservoir. Theexpansion reservoir is connected to the low pressure region of theaspirator in the discharge line of the tank, and when water is drawnfrom the tank through the aspirator, the aspirator action draws waterfrom the expansion reservoir, which mixes with the discharging waterfrom the tank. In order to avoid temperature dilution (water from thereservoir reducing the temperature of the water discharged from thetank) the expansion reservoir must be placed in heat exchangerelationship with the tank itself, or some auxiliary heating system mustbe provided to independently heat the reservoir. An additionaldisadvantage of this form of system is the tendency of water in theexpansion reservoir to become stagnant. Also, the vent normally providedin the expansion reservoir which also vents the tank tends to becomewaterbound in the zone of the aspirator and consequently water tends tohang back in the tank discharge line at the end of each drink dispensecycle, and this water subsequently drips at random from the dischargeline. As yet another disadvantage of such systems, percolation tends tooccur at the aspirator during heating cycles because of the relativelysmall capacity of the aspirator and this also causes water to drip fromthe discharge tube. To avoid this problem operators frequently reduceoperating temperatures to approximately F., which is at the very lowerend of the acceptable temperature range. And scaling is anotherphenomena which is particularly troublesome at the aspirator, and causesclogging and erratic operation. And all of the prior art systemsdescribed are susceptible to tank burn out as a result of thermostatfailure.

OBJECTS AND FEATURES One important object of this invention is toprovide a beverage dispenser with a hot water system which eliminatesmany of the disadvantages of pressurized and atmospheric tanks asdescribed above'in connection with the prior art. 7

A more specific object of this invention is to provide a hot watersystem for beverage dispensers having a closed atmospheric pressure tankthat employs an expansion reservoir which does not dilute thetemperature of the water discharged from the tank.

Another specific object of this invention is to provide a hot watersystem for beverage dispensers employing an atmospheric closed tank,which provides greater freedom of choice of water temperature.

Yet another important object of this invention is to provide a hot watersystem for beverage dispensers, which minimizes vapor losses.

tern.

To accomplish these and other objects, the hotbeverage dispenser of thisinvention includes a hot water system having a closed hot water tankthat operatesat atmospheric pressures, with an inlet orfilllineconnected to the bottom. An aspirator isdisposed in the inletline, and an expansion reservoir is disposed at an elevation so that itsvertical extent spans thetop, of the tank. A duct connects the'expansionreservoir to the low pressure region of the aspirator, and a dischargeline extends from the top ofthe tank for drawingwater from the tank tothe mixing chamber in the dispenser where the hot water is mixed withthe flavor concentrate. it

will be better understood and appreciatedfrom thefolin the accompanyingdrawing in which:

BRIEF FIGURE DESCRIPTION type fill system for the hot water tank 18.That is, when FIG. 1 is a perspective view of a beverage dispenserconstructed in accordance with this invention; and" FIG. 2 is adiagrammaticside view of the beverage dispenser shown in FIG. 1illustrating the hot water sys- DETAILED DESCRIPTION OF PREFERREDEMBODIMENT typically be of the variable orifice type'which varies d vwith pressure so that a constant flow rate is maintained The beveragedispenser shown in the drawing is of" the class of beverage dispensersshown in US. Pat. No.

3,568,887 datedMar. 9, 1971 and copending applica-a tions Ser. Nos.887,671 and 36,863 filed Dec. 23, 1969 and May 13, 1970 respectively,all assigned to Je t.

use with flavor syrup, the invention of the present ap- Spray Cooler,Inc., Waltham, Massachusetts. The hot water system of the presentinvention is' an improvement over the hot water systemsshown in thepatent and earlier patent applications. The hotwatersystem is suitablefor use withbeverage systems employing either syrup or powder astheflavor source. The system is also suitable for use in .othr formsoffooddispensers quired.

The beverage dispenser ofFIG. 1 includes housing 10 that contains asyrup delivery circuit (not shown) as such as soup dispensers .or whereplain hot waterjis retom of its front wall and amixing chamber;l4 on the7 front wall above the tray 12. A typical assembly 14 is shown anddescribed in detail in US. Pat. No. 3,568,887, supra.

In FIG. 2 the hot water system 11 which supplies priate support andcontains an immersion heater 22 for heating the water in the tank to thedesired temperaor hoseto the dispenser.

An inlet duct 28 extends from the rear wall 30 of the housing tothebottom 32 of the tank through a solenoid valve40, flow regulating device38,proportioning assembly PA, T-connection 34 and drain tube 36. The

drain tube extends through the bottom wall of the housing 10 and as itsname suggests, affords means for emptying the hot water tank 18 for anyreason. Ordi- I narily; a stopper 37 isthreaded into the drain tube 36so that the tube is inactive except as forming part of the inlet duct 28for filling the tank. A fitting 39 is conected to the end of the inletduct28 outside a rear wall of 1 the housing to afford means for couplinga water pipe The flow regulatingdevice 38 and solenoid valve 40interrupttheinlet duct ZSinsidethe dispenser housing 10 and togetherconstitute a conventional displacement the solenoid'valve is open, waterenters the tank 18, arid an equal volume of water isdisplaced out thetank discharge pipe 42 in a manner which is explained in greater detailbelow. The flow regulating valve 38 may whenever the valveis open.

portioning assembly suggested in FIG. 2 is designed for plication is notlimited to beverage dispensers which use syrup. As pointed out above,the invention has j equal utility in dispenserswhich employ powder asthe flavor medium. t

An aspiratorin the form of a jet pump orother means 44fisprovidedin theinl et duct 28 downstream of the t s olenoid 40 and proportioningassembly PA, and an expansion reservoir; 46 through its standpipe48 isconnectedtoithe lowpressure region of theaspirator 44. In FIG.f2 theexpansion reservoir 46, standpipe 48,por-

scribe a U-tube configuration. The vent pipe 50 con- 7 tion 28a of inletduct 28 and tank 18 are shown to denected to the top of the expansionreservoir establishes a head of atmospheric pressure above the liquid inthe reservoir. Because the standpipe 48 is connected to the low.pressure region of the aspirator 44, flow into the tank 18 through theinlet or fill duct 28 will draw water from the reservoir 46 into. tank18.

The vent pipe 50 is connected to the front wall 51 of the housing 10 soas to provide an outlet 52 immediately abovethe drip tray 12. Thedischarge pipe 42 l which is the outletfrom the hot water tank 18 isconnected directly to the mixing chamber 14 through the ture. While inthe embodiment shown the heater is an not critical to the presentinvention. As shown in FIG.

2, a thermostat 24 is mounted on the tank wall 26,

which will ordinarily be disposed in theheatercircuit (not shown) so asto control operation ofthe heater 22 and thereby governwatertemperature.

front wall 51 of the housing. A passage 54 joins the vent pipe 50withthe discharge pipe 42. In order for an op erator to draw a hot drinkfrom the dispenser, the actuator button 56 is depressed which places inoperation the controlcircuit (not shown) within the housing 10.

The dispense cycle includes a period during which the solenoidvalv e 40in the fill pipe 28 in the hot water system isopen, which causes waterto be displaced from the tank 18 out the discharge pipe 42 and flowtothe mixing chamber Atthe mixing chamber the hot water is mixed witheither syrup or powder, whichever is used in the particular dispenser,and the mixed water and flavor medium is discharged through the spout58. In the embodiment shown, a selector dial 60 is suggested whichallows for the selection of a large or small drink. Such an arrangementis shown in detail'in U.S. Pat. No. 3,563,887, supra.

The expansion reservoir 46 in the system is not in physical contact withthe heating tank 18. It is elevated to a level which is coincident withthe normal operating water levels within the tank 18 and its verticaloutlet 42b which forms part of discharge pipe 42. Under staticconditions with the hot water tank 18 full and the solenoid valve 40closed, the water in the hot water tank will backflow by gravity out thedrain portion 28a of the inlet duct and up the standpipe 48 and intoreservoir 46 until an equilibrium is reached.

Because water is fed to the mixing chamber 14 by literally displacing itfrom tank 18, it is essential that the tank 18 be maintained full and abalance must be maintained with the volume of water collected in thevertical portion of the standpipe 48 and expansion chamber 46. It alsowill be appreciated that because the solenoid valve 40 is controlled bya timed cycle, the amount of water entrained from the expansion chamber46 and standpipe 48 during a given period must be maintained constantfor it supplements the water drawn through the inlet duct 28 in fillingthe tank 18. If the volume of water entrained from the expansion chamberand standpipe varies, then the amount of water fed into the tank 18during any given period will not be constant, and consequently the sizeof drinks dispensed by the dispenser will vary. And the volume of waterin the expansion reservoir and standpipe must always be larger than canbe aspirated during the longest possible drink dispense cycle to avoidcompletely draining the reservoir and standpipe.

Typically, the aspiration rate may be approximately 1 cc/second when theflow rate through the aspirator is 39 cc/second. With a total volume ofapproximately 15 cc in the reservoir and standpipe, the maximum lengthof drink dispense time would be 15 seconds, after which air would bedrawn into the tank with the water from the main supply. The airdischarging from the tank 18 through outlet pipe 42 would createturbulence in the line and cause some flow of water into the vent 50through the bypass 54.

The significance of this balance between the tank 18 andreservoir-standpipe combination is greatest when the dispenser is beingoperated in so-called fast service installations where the use rateapproximates the mechanical speed of the dispenser. If the water tank 18is filled cold and then heated, the water will expand upwardly in thetank causing the level to rise in the expansion leg composed of thereservoir 46 and pipe 48, until maximum temperature is achieved. Thislevel may be represented as an expansion from A to B in FIG. 2, and theratio of the volume per increment of height between the tank dischargepipe 42 and the reservoir 46 is such that the bulk of the expansionwater is collected in the reservoir before reaching the level of the topof down run 42a in pipe 42. If malfunctioning occurs, the excess waterwill exit from the expansion reservoir 46 through pipe 50 and its outlet52 to the drip tray 12. so as to avoid an objectionable drip from thespout 58 of mixing chamber 14. Thus spillover is avoided.

Under fast draw conditions, (perhaps four drinks per minute) the actionof the aspirator will draw some water out of the expansion reservoir 46during each drink cycle. If the drink cycle is 5 seconds and theaspiration rate is Ice/second, Scc will be removed from theexpansion'reservoir with each drink. This is substantially offset by theexpansion of the incoming cold water in the tank. If the drink consumes6 ounces of water, then that amount of cold water introduced into thetank and heated from 32 to 212 F. will result in an expansion ofapproximately 4cc. While it would appear that the reservoir-standpipecombination would eventually drain because of the difference betweenoutflow and expansion under sustained draw conditions, this does notactually occur because the head in the reservoir and standpipedecreases, which reduces the'aspiration rate. This reduction inaspiration rate is sufficient to prevent the siphon leg comprising thereservoir and standpipe from being drained.

Another advantage of the present invention is that it avoids dilution ofdrink temperature. By feeding the water from the expansion reservoir andstandpipe into the cold inlet line to the tank, expansion water has noeffect upon the temperature of the water in the discharge pipe 42.

It will also be appreciated that in this particular hot water system,the diameter of the discharge pipe 42 is not critical to the performanceof the dispenser, and the line typically may be of one-half inchdiameter. This minimizes resistance to discharge flow and reduces thepossibility of a block in the line caused by scale build-up. Further,there is no aspirator in the discharge line to promote nucleate boilingwhich may cause water to spurt from the outlet.

Another advantage of the present system is the minimum effect of vaporlosses upon drink size. In prior art devices with the aspirator locatedin the discharge pipe, when the level of water in the discharge pipefalls below the aspirator no transfer of water from the expansionreservoir to the tank occurs, and with evaporation the level of water inthe discharge pipe continues to drop. As a result, the first drinkdischarged from the dispenser after a prolonged shutdown (over aweekend) is short due to the vapor losses. On the contrary, in thepresent system the U-tube arrangement maintains the expansion reservoirin constant effective communication with the tank and its discharge pipeso that'changes in drink size are not discernable.

And yet another advantage of the hot water system of this invention isthat when the tank is drained, the expansion reservoir also drains.Consequently, during shipment or periods of storage when it is desirableto drain the water system completely to avoid the possibility ofstagnation or prevent damage from freezing, merely by opening the drainpipe 36 completely drainage is effected.

Still another advantage. of the present system is that it providescomplete drain-down of water in the discharge line to the mixing chamber14 during each dispense cycle. During the normal cycle, the inlet waterpressure entering through inlet duct 28 forces water out the top of thetank and keeps the discharge tube 42 full until the solenoid 40 closesat the end of the cycle. At that instant, the water in the vertical leg42b of the discharge line 42 above the tank drains back into the tankis, while the water in the down tun 42a ofdischarge line 42 runs out tothe mixing chamber 14 and into the drink. In the prior art systems, thewater may not drain back into the tank, but rather drains into theexpansion reservoir. This often causes a blockage of the vent in theexpansion reservoir so that it is no longer in communication with thetank. Consequently, water in the down run 42a cannot discharge freelyinto the mixing chamber but rather slowly drips from it as air isgradually vented through the water column. It will also be appreciatedthat the bypass 54 provides a safety drain for the system in the event ablockage occurs in the mixing chamber 14. From the foregoing descriptionit is evident that the present invention has many advantages over theprior art. The combination of improvements offer'substan tially betterperformance than may be derived from the prior art systems.

What is claimed is:

l. A hot water system forbeveragedispensers com prising a hot water tankand a heater disposed in heat exchange relationshipwith the tank toheatwater introduced into the tank,

a water inlet line connected to the bottom of the tank and meansincluding a valve in the line for regulating the flow of water to thetank,

an aspirator in the line between the .valve and tank,

an expansion reservoir disposed at an elevation so that its verticalextent spans the top of the tank,

a duct connected atone end to the low pressure region of the aspiratorand at the other end to the expansion reservoir,

an expansion and overflow port formed in the expansion reservoiradjacent the top,

" and a discharge line connected to the topof the tank 7 [characterizedby a said reservoirand tank beingphysically separated so. u

a hot water tank and a heater disposed in heatex i change relationshipwith the tank to heat water introduced into the tank, A I *1 a waterinlet line connected to the bottom of the tank and means including avalve in the line for regulating the flow of water to the tank,

an aspirator in the line between the valve and tank,

an expansion reservoir disposed at anelevation so that its height spansthe top of the'tank, a duct connected at one. end to the low perssu reregion of the aspirator and at the other end to the expansion reservoir,7 e an expansion and overflow port formed in the expancharacterized bysion reservoir adjacent the top,

and a discharge line connected to the top of thetank V to direct waterfrom the tank to the mixing unit. 7 3. A hot beverage dispenserasdescribed in claim 2 further characterized by said expansionandoverflow port in the reservoir being connected to the atmosphere;

and a'passage connecting the overflow'port and the sure region thereinwhen water flows through the lineinto the tank, an expansion reservoirdisposed at an tank both when the water is cold and heated, i

a duct connecting the reservoir and the low pressure region in the line,t and a discharge line connected to the tank.

'5. A hotrwater system asdescribed in claim 4 further characterized bysaid inlet line 6. A hot watersystem as described in claim 4 further avalve in the inlet line controlling the discharge of water from thetankthrough the outlet line.

7. A hot water system asdescribed in claim 6 further characterized by ion the inletline.

8. A hot water system as asto be free of heatexchange relationship withone another. M

9. A hot water system as described in claim 7 further characterized by Vt t said discharge line beingfree of restrictions adjacent the topj'ofthe tank and "half inch diameter line; 10. A hot water system asdescribed ther characterized by t an ove the topof the reservoir, a hoseconnected to said; port to carry the overflow l of the reservoir to'aremote point, a

in claim 7 furand a line connecting 'the hose and the dischargeelevation so that its height spans the normal level of water in thebeing connected to the bottom of the I a tank and the outlet lirie tothe top Of the tank.

:said valvebeing upstream of the low pressure region described in claim4further 7 being approximately one- 1 rflow and expansion portprovidedadj acen t

1. A hot water system for beverage dispensers comprising a hot watertank and a heater disposed in heat exchange relationship with the tankto heat water introduced into the tank, a water inlet line connected tothe bottom of the tank and means including a valve in the line forregulating the flow of water to the tank, an aspirator in the linebetween the valve and tank, an expansion reservoir disposed at anelevation so that its vertical extent spans the top of the tank, a ductconnected at one end to the low pressure region of the aspirator and atthe other end to the expansion reservoir, an expansion and overflow portformed in the expansion reservoir adjacent the top, and a discharge lineconnected to the top of the tank to direct heated water from the tank.2. A hot beverage dispenser comprising a housing, a hot water systemmounted in said housing a mixing unit mounted on the housing forcombining hot water and a flavor concentrate, said hot water systemincluding a hot water tank and a heater disposed in heat exchangerelationship with the tank to heat waTer introduced into the tank, awater inlet line connected to the bottom of the tank and means includinga valve in the line for regulating the flow of water to the tank, anaspirator in the line between the valve and tank, an expansion reservoirdisposed at an elevation so that its height spans the top of the tank, aduct connected at one end to the low perssure region of the aspiratorand at the other end to the expansion reservoir, an expansion andoverflow port formed in the expansion reservoir adjacent the top, and adischarge line connected to the top of the tank to direct water from thetank to the mixing unit.
 3. A hot beverage dispenser as described inclaim 2 further characterized by said expansion and overflow port in thereservoir being connected to the atmosphere, and a passage connectingthe overflow port and the discharge line.
 4. A hot water system forbeverage dispensers comprising a tank and a heater associated therewithfor raising the temperature of the water in the tank, a water inlet lineconnected to the tank, means provided in the inlet line creating a lowpressure region therein when water flows through the line into the tank,an expansion reservoir disposed at an elevation so that its height spansthe normal level of water in the tank both when the water is cold andheated, a duct connecting the reservoir and the low pressure region inthe line, and a discharge line connected to the tank.
 5. A hot watersystem as described in claim 4 further characterized by said inlet linebeing connected to the bottom of the tank and the outlet line to the topof the tank.
 6. A hot water system as described in claim 4 furthercharacterized by a valve in the inlet line controlling the discharge ofwater from the tank through the outlet line.
 7. A hot water system asdescribed in claim 6 further characterized by said valve being upstreamof the low pressure region on the inlet line.
 8. A hot water system asdescribed in claim 4 further characterized by said reservoir and tankbeing physically separated so as to be free of heat exchangerelationship with one another.
 9. A hot water system as described inclaim 7 further characterized by said discharge line being free ofrestrictions adjacent the top of the tank and being approximatelyone-half inch diameter line.
 10. A hot water system as described inclaim 7 further characterized by an overflow and expansion port providedadjacent the top of the reservoir, a hose connected to said port tocarry the overflow of the reservoir to a remote point, and a lineconnecting the hose and the discharge lines.